Recently, wireless local area network (WLAN) protocols whose wireless coverage range is short have been developed considering the mobility. Examples of the WLAN protocols are Wi-Fi, Bluetooth, ZigBee, and the like. WLAN protocols define a variety of technical standards to connect systems to a wired network via access points (APs). WLAN protocols include 802.11b and 802.11g protocols, which uses 2.4 GHz frequency band, and 802.11a protocol that uses 5 GHz frequency band. WLAN protocols allow for communication using a plurality of channels. For example, 802.11b and 802.11g protocols each include 14 channels that are spaced 5 MHz apart except for a 12 MHz spacing before last channel, that is, Channel 14. However, the 802.11b and 802.11g protocols each require 25 MHz of channel separation, adjacent channels overlap and will interfere with each other.
With the development of communication technology, portable terminals supporting WLAN protocols, such as Wi-Fi, and the like, are increasing. These portable terminals can wirelessly establish communication channels with APs and provide Internet services through the APs. The portable terminals supporting a Wi-Fi protocol are configured to establish a fixed wireless communication channel with APs. That is, the conventional portable terminals establish a wireless communication channel with a particular AP, using a preset channel, and do not change the channel. Therefore, if a plurality of APs use the same channel or adjacent channels, the wireless communication channel between the portable terminal and the AP may be congested due to frequency interference. That is, if a plurality of APs, located close to a portable terminal, use the same channel or adjacent channels, the portable terminal experiences the decrease of the communication speed and the disconnection of the communication channel.